Apparatus for stopping adaptive filtering when valid received signal detected and for limiting signal to be demodulated

摘要

A digital signal receiving apparatus includes: detection-judging portion (19) judging a possible presence of a desired signal when a signal level of a smoothed signal (A1(t)) is greater than a reference level (A2(t)); a filter controlling portion (20) switching an adaptive filter (16) from an adaptive mode to a non-adaptive mode when the detection-judging portion (19) judges the possible presence of the desired signal and switching from the non-adaptive mode to the adaptive mode when the detection judging portion (19) judges the absence of the desired signal; a limiting portion (18a) limiting a signal level of an auto-correlation signal (X(t)) to the signal level of the smoothed signal (A1(t)); and a demodulating portion (18b) demodulating the auto-correlation signal (X(t)) having the signal level limited by the limiting means so as to generate a demodulated signal.